This application is based on and claims priority to Japanese Patent Application No. 2000-215164, filed Jul. 14, 2000, the entire contents of which is hereby expressly incorporated by reference.
1. Field of the Invention
This invention relates to an engine for a watercraft, and more particularly to an improved lubrication system of an engine for a watercraft.
2. Description of Related Art
Although two cycle internal combustion engines have been the accepted powerplant for use in outboard motors for a long time, four cycle engines are becoming more popular due to their superior performance. This presents some significant problems to the designer because of the more complicated nature of a four cycle engine when compared to a two cycle engine. One of the complicating factors with applying four cycle engines to outboard motors is the lubrication system design for such engines.
The four-cycle engine has a crankcase which is located generally toward the front of the engine and in which lubricant collects. Once in the crankcase, the lubricant circulates to the various moving components to assure smooth operation and also to reduce wear of those components. The lubricant is added to the engine crankcase when the engine is first put into service, and later as needed. Typically, the lubricant is added into the crankcase through a lubricant filler structure.
The conventional lubricant filler structure is located on the rear side of the engine, opposite from the crankcase. This creates at least two problems. Rear-side positioning of the oil filling unit tends to increase the size of the engine because longer and more complicated conduits are required to direct the lubricant from the rear side into the crankcase, which is located on the front side. In addition to increasing the size of the engine, rear-side positioning of the lubricant filler structure makes the unit inaccessible to a user of a watercraft on which the motor is mounted because the user has to reach from inside the watercraft, beyond the crankcase, and around the casing enclosing the engine.
A need therefore exists for an outboard motor engine with improved access to the lubricant filler structure for an operator who is located in the watercraft on which the motor is mounted.
Accordingly, one aspect of the present invention involves an outboard motor that comprises a drive unit, and a bracket assembly adapted to be mounted on an associated watercraft to support the drive unit. The drive unit comprises an internal combustion engine. The engine comprises an engine body that includes a crankcase and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. The engine further comprises an intake passage for introducing air into the combustion chamber. The intake passage extends from a rear portion of the combustion chamber to an external side of the crankcase and to a forward side of the crankcase. The intake passage and the crankcase define a space therebetween. The engine also comprises a lubricant filler structure that includes a cap, and a lubricant filler tube having a lower end connected to the crankcase and an upper end forming a filling port. At least a portion of the lubricant filler structure is disposed within the space defined by the crankcase and the intake passage.
Another aspect of the present invention involves an internal combustion engine comprising an engine body that includes a crankcase and a moveable member moveable relative to the engine body. The engine body and the moveable member together define a combustion chamber. The engine also comprises a lubricant filler structure that comprises a cap, and a lubricant filler tube having a lower end connected to the crankcase and an upper end forming a filling port. The filler tube is disposed forwardly at an angle with respect to the vertical.
A further aspect of the present invention involves an internal combustion engine for use with its crankshaft extending in a generally vertical direction. The internal combustion engine comprises an engine body. The engine body comprises a crankcase member, a cylinder block and a cylinder head. The crankcase member and the cylinder block are joined together to define a crankcase chamber. The crankshaft extends in a generally vertical direction through the crankcase chamber. At least one cylinder bore is formed in the cylinder block and a piston is reciprocally mounted within the cylinder bore. The piston is connected to the crankshaft. A flywheel is secured to the crankshaft and is disposed above an upper surface of the engine body. A cover member extends over the flywheel. An oil fill tube is connected to an upper portion of the crankcase member and the oil fill tube extends away from the cylinder head at an angle.